In a typical cellular radio system, a wireless communication device may communicate via a radio access network (RAN) to a core network. The wireless communication device may be any of a number of device types, such as a mobile telephone (also known as cellular or cell phones), lap top with wireless communication capability, personal digital assistant (PDA), etc. These may be portable, hand held, pocket sized, installed in a vehicle etc and communicate voice and/or data signals with the radio access network.
In a Universal Mobile Telecommunications System (UMTS) network, a wireless device may perform cell reselection upon determining that reselection criteria are fulfilled (e.g., a higher ranked neighbor cell is found based on various ranking criteria calculated using measurements and parameters from system information). Once the better neighbor cell is identified, the cell reselection procedure may involve starting a reselection timer that is configured to introduce hysteresis in the time domain (i.e., a delay). If the reselection criteria are still present once the reselection timer expires, the wireless device may perform reselection by decoding system information blocks (SIBs) of the indentified better neighbor cell, followed by a cell update procedure to update the controlling radio network controller (RNC).
Sources of delay in the typical cell reselection procedure may be the hysteresis delay and time that it takes to decode the SIBs of the better neighbor cell after cell reselection timer expires. When the serving cell is performing poorly, if the device is in a radio resource control (RRC) connected mode, the decoding/reading of the SIBs and cell update procedure may significantly degrade the data rate. In certain existing single-SIM devices, such delay may be mitigated by setting the reselection timer to zero, thereby causing decoding of SIBs and cell reselection immediately after better a neighbor cell is identified. However, since tune-away is not allowed during cell reselection, dual-SIM (e.g., DSDS) devices may experience decreased performance on a second SIM due to decoding SIBs for a first SIM after expiration of the reselection timer.